FEM: Purge tool deletes all result objects. Fixes #23028

- Correctly deletes children of pipeline without error on delete
- Ensures visualizations are also deleted as they are result objects too
- Ensures purge tool uses a transaction, like all tools should

src/Mod/Fem/App/FemPostGroupExtension.cpp

@@ -109,11 +109,8 @@ App::DocumentObject* FemPostGroupExtension::getGroupOfObject(const App::Document
 
 void FemPostGroupExtension::onExtendedUnsetupObject()
 {
-    // remove all children!
-    auto document = getExtendedObject()->getDocument();
-    for (const auto& obj : Group.getValues()) {
-        document->removeObject(obj->getNameInDocument());
-    }
+    // remove all children (if not already removed)!
+    removeObjectsFromDocument();
 }
 
 bool FemPostGroupExtension::allowObject(App::DocumentObject* obj)

src/Mod/Fem/femcommands/commands.py

@@ -926,7 +926,9 @@ class _ResultsPurge(CommandManager):
     def Activated(self):
         import femresult.resulttools as resulttools
 
+        FreeCAD.ActiveDocument.openTransaction("Purge FEM results")
         resulttools.purge_results(self.active_analysis)
+        FreeCAD.ActiveDocument.commitTransaction()
 
 
 class _SolverCalculixContextManager:

src/Mod/Fem/femobjects/base_fempostvisualizations.py

@@ -80,6 +80,7 @@ class PostVisualization(base_fempythonobject.BaseFemPythonObject):
 
     def __init__(self, obj):
         super().__init__(obj)
+        self.Type = "Fem::FemPostVisualization"
         obj.addExtension("App::GroupExtensionPython")
         self._setup_properties(obj)
 

src/Mod/Fem/femresult/resulttools.py

@@ -75,6 +75,12 @@ def purge_results(analysis):
             analysis.Document.removeObject(m.Name)
     analysis.Document.recompute()
 
+    # remove visulizations
+    for m in analysis.Group:
+        if is_of_type(m, "Fem::FemPostVisualization"):
+            analysis.Document.removeObject(m.Name)
+    analysis.Document.recompute()
+
 
 def reset_mesh_deformation(resultobj):
     """Resets result mesh deformation.